Air conditioner

ABSTRACT

A refrigerant circuit of an air conditioner includes a compressor unit, an evaporator, and a solenoid valve comprising a flow control mechanism. The operation capacity of the compressor unit is adjusted by changing the number of compressors in operation. The evaporator includes a first heat exchanger section and a second heat exchanger section. A first flow pass of the first heat exchanger section and a second flow pass of the second heat exchanger section are connected to each other in parallel. In the state where the solenoid valve is open, refrigerant flows into both of the first flow pass and the second flow pass. In the state where the solenoid valve is closed, refrigerant flows only to the first flow pass.

TECHNICAL FIELD

The present disclosure relates to air conditioners which cool the air tobe supplied to an indoor space through an air passage, such as a duct.

BACKGROUND ART

Air conditioners which cool the air to be supplied to an indoor spacethrough a duct have been known. The air cooled by the air conditionersflows in the duct and is distributed into a plurality of rooms.

The air conditioners of this type are disclosed in Patent Document 1,for example. Patent Document 1 shows a marine air conditioner. In thisair conditioner, the air that is cooled when it passes through anevaporator flows in a duct, and is supplied to a plurality of cabins.

CITATION LIST Patent Document

Patent Document 1: Japanese Patent Publication No. 2008-008543

SUMMARY OF THE INVENTION Technical Problem

The air conditioner disclosed in Patent Document 1 includes a pluralityof compressors and one evaporator. Evaporators of the air conditionersof this type are designed to be capable of reliably evaporating arefrigerant while all the compressors are in operation. Further, in theair conditioner having a plurality of compressors, the number ofcompressors in operation needs to be changed according to an airconditioning load. Thus, in a situation where only some of the pluralityof compressors are in operation, the capacity of the evaporator isrelatively too much, and all the compressors may have to be stoppedbecause of too much air-conditioning capability with respect to the airconditioning load, regardless of a reduction in the number ofcompressors in operation.

During operation of the compressors, moisture in the air is condensedinto drain water in the evaporator. If all the compressors are stoppeddue to too much air-conditioning capability with respect to the airconditioning load, air is not cooled by the evaporator. In thissituation, the drain water remaining around the evaporator is heated bythe air passing through the evaporator, evaporated again, and suppliedto an indoor space together with the air, which may increase thehumidity of the indoor space, and reduce comfort of the space.

The present disclosure is thus intended to reduce the occurrence ofsituation where all compressors are stopped during operation of an airconditioner, and maintain high level of comfort of an indoor space.

Solution to the Problem

The first aspect of the present disclosure is directed to an airconditioner (10) including a refrigerant circuit (20) which performs arefrigeration cycle by circulating a refrigerant, for cooling airflowing in an air passage connected to a supply opening (102) of each ofa plurality of rooms by the refrigerant. The refrigerant circuit (20)includes a compressor unit (30) having a plurality of compressors (31,32, 33) connected to each other in parallel, an evaporator (50) providedat the air passage and having a plurality of heat exchanger sections(55, 60, 65) connected to each other in parallel to heat exchange therefrigerant with the air, and a flow control mechanism (17) configuredto change the number of the heat exchanger sections (55, 60, 65) throughwhich the refrigerant passes.

In the first aspect of the present disclosure, the refrigerant circuit(20) performs a refrigeration cycle. Air is cooled in the evaporator(50) of the refrigerant circuit (20). The air cooled in the evaporator(50) passes through the air passage and is distributed into a pluralityof rooms. In the compressor unit (30), a plurality of compressors (31,32, 33) are connected in parallel to each other. The operation capacityof the compressor unit (30) varies by changing the operation capacity ofeach of the compressors (31, 32, 33), or changing the number ofcompressors (31, 32, 33) in operation. The evaporator (50) includes aplurality of heat exchanger sections (55, 60, 65). In the evaporator(50), the plurality of heat exchanger sections (55, 60, 65) areconnected in parallel to each other. For example, in the case where therefrigerant flows into all of the heat exchanger sections (55, 60, 65),the refrigerant sent to the evaporator (50) is distributed to the heatexchanger sections (55, 60, 65), takes heat from the air, andevaporates. The number of heat exchanger sections (55, 60, 65) to whichthe refrigerant flows is changed by the flow control mechanism (17). Thecapacity of the evaporator (50) is changed by changing the number ofheat exchanger sections (55, 60, 65) to which the refrigerant flows.

The second aspect of the present disclosure is that in the first aspectof the present disclosure, the flow control mechanism (17) changes thenumber of the heat exchanger sections (55, 60, 65) through which therefrigerant passes, according to an operation capacity of the compressorunit (30).

In the second aspect of the present disclosure, the capacity of theevaporator (50) is changed according to the operation capacity of thecompressor unit (30). If the operation capacity of the compressor unit(30) changes, the flow rate of the refrigerant which passes through theevaporator (50) also changes. Thus, it is possible to adjust thecapacity of the evaporator (50) according to the flow rate of therefrigerant which passes through the evaporator (50) by changing thenumber of heat exchanger sections (55, 60, 65) through which therefrigerant flows according to the operation capacity of the compressorunit (30).

The third aspect of the present disclosure is that in the second aspectof the present disclosure, each of the compressors (31, 32, 33) in thecompressor unit (30) has a fixed capacity, the compressor unit (30) isconfigured such that the operation capacity of the compressor unit (30)is adjusted by changing the number of the compressors (31, 32, 33) inoperation, and the flow control mechanism (17) reduces the number of theheat exchanger sections (55, 60, 65) through which the refrigerantpasses, when the number of the compressors (31, 32, 33) in operation isreduced.

In the third aspect of the present disclosure, the operation capacity ofthe compressor unit (30) is adjusted by changing the number ofcompressors (31, 32, 33) in operation. Thus, the operation capacity ofthe compressor unit (30) is changed in stages. If the number ofcompressors (31, 32, 33) in operation is reduced and the operationcapacity of the compressor unit (30) is accordingly reduced, thecapacity of the evaporator (50) is reduced by the flow control mechanism(17). That is, if the operation capacity of the compressor unit (30) isreduced and the flow rate of the refrigerant passing through theevaporator (50) is reduced, the capacity of the evaporator (50) isaccordingly reduced.

The fourth aspect of the present disclosure is that in any one of thefirst to third aspects of the present disclosure, the refrigerantcircuit (20) is provided with one expansion valve (40) which expands therefrigerant that is not yet branched for flowing into the heat exchangersections (55, 60, 65) of the evaporator (50).

In the fourth aspect of the present disclosure, the refrigerant circuit(20) is provided with one expansion valve (40). The refrigerant whichcirculates in the refrigerant circuit (20) expands when it passesthrough the expansion valve (40), and thereafter the refrigerant isdistributed into each of the heat exchanger sections (55, 60, 65) of theevaporator (50).

The fifth aspect of the present disclosure is that in any one of thefirst to third aspects of the present disclosure, the refrigerantcircuit (20) is provided with a plurality of branch pipes (26, 27, 28)each of which is connected to a corresponding one of the heat exchangersections (55, 60, 65) of the evaporator (50), and through which therefrigerant that is branched for flowing into the heat exchangersections (55, 60, 65) flows, and each of the branch pipes (26, 27, 28)is provided with a corresponding one of expansion valves (41, 42, 43)which expand the refrigerant.

In the fifth aspect of the present disclosure, the refrigerant circuit(20) is provided with the same number of expansion valves (41, 42, 43)as the number of heat exchanger sections (55, 60, 65) of the evaporator(50). The refrigerant which circulates in the refrigerant circuit (20)is branched for flowing into the heat exchanger section (55, 60, 65) ofthe evaporator (50), then passes through the expansion valve (41, 42,43) and is expanded, and thereafter flows into the heat exchangersection (55, 60, 65) corresponding to the expansion valve (41, 42, 43)through which the refrigerant passes.

Advantages of the Invention

In the present disclosure, the capacity of the evaporator (50) ischanged by changing the number of heat exchanger sections (55, 60, 65)to which the refrigerant flows, using the flow control mechanism (17).Thus, if the operation capacity of the compressor unit (30) is reducedto make the air-conditioning capability of the air conditioner (10)accord with the air conditioning load, the air-conditioning capabilityof the air conditioner (10) can be reliably reduced by reducing thenumber of heat exchanger sections (55, 60, 65) to which the refrigerantflows and thereby reducing the capacity of the evaporator (50). As aresult, a lower limit of a range of adjustment of the air-conditioningcapability of the air conditioner (10) can be reduced to a point lowerthan before, and it is possible to reduce the frequency of occurrence ofthe situation where all the compressors (31, 32, 33) are stopped duringoperation of the air conditioner (10). That is, according to the presentdisclosure, it is possible to reduce the occurrence of a phenomenon inwhich drain water evaporates again in the state where all thecompressors (31, 32, 33) are stopped, and is delivered into an indoorspace, and maintain high level of comfort of the indoor space.

In the second aspect of the present disclosure, the number of heatexchanger sections (55, 60, 65) through which the refrigerant passes ischanged according to the operation capacity of the compressor unit (30).Thus, the capacity of the evaporator (50) can be adjusted according tothe flow rate of the refrigerant which passes through the evaporator(50). According to the present disclosure, the capacity of theevaporator (50) can be set appropriately, and the air-conditioningcapability of the air conditioner (10) can be adjusted moreappropriately.

In the third aspect of the present disclosure, if the number ofcompressors (31, 32, 33) in operation is increased/reduced, the numberof heat exchanger sections (55, 60, 65) through which the refrigerantpasses is accordingly increased/reduced. Thus, according to the presentdisclosure, the capacity of the evaporator (50) can be appropriatelychanged according to the operation capacity of the compressor unit (30)which is changed in stages, thereby making it possible to adjust theair-conditioning capability of the air conditioner (10) moreappropriately.

In the fourth aspect of the present disclosure, the refrigerant flowinginto all the heat exchanger sections (55, 60, 65) can be expanded usingone expansion valve (40). Thus, according to the present disclosure, anincrease in the number of components of the air conditioner (10) can beprevented.

In the fifth aspect of the present disclosure, the flow rate of therefrigerant flowing into the heat exchanger sections (55, 60, 65) can beindividually controlled by adjusting the openings of the expansionvalves (41, 42, 43) which respectively correspond to the heat exchangersections (55, 60, 65). Thus, according to the present disclosure, theflow rate of the refrigerant flowing through the heat exchanger sections(55, 60, 65) of the evaporator (50) can be appropriately adjusted, andthe air-conditioning capability of the air conditioner (10) can bemaximized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration of a marine air-conditioning system.

FIG. 2 is a schematic configuration of an air conditioner.

FIG. 3 is a configuration of a main part of a refrigerant circuitaccording to the first variation of the first embodiment.

FIG. 4 is a configuration of a main part of a refrigerant circuitaccording to the first variation of the first embodiment.

FIG. 5 is a configuration of a main part of a refrigerant circuitaccording to the second variation of the first embodiment.

FIG. 6 is a configuration of a main part of a refrigerant circuitaccording to the second embodiment which corresponds to the refrigerantcircuit of FIG. 2.

FIG. 7 is a configuration of a main part of a refrigerant circuitaccording to the second embodiment which corresponds to the refrigerantcircuit of FIG. 3.

FIG. 8 is a configuration of a main part of a refrigerant circuitaccording to the second embodiment which corresponds to the refrigerantcircuit of FIG. 4.

FIG. 9 is a configuration of a main part of a refrigerant circuitaccording to the second embodiment which corresponds to the refrigerantcircuit of FIG. 5.

FIG. 10 is a configuration of a main part of a refrigerant circuitaccording to the second embodiment which corresponds to the refrigerantcircuit of FIG. 6.

FIG. 11 is a configuration of a main part of a refrigerant circuitaccording to the first variation of another embodiment which correspondsto the refrigerant circuit of FIG. 2.

FIG. 12 is a configuration of a main part of a refrigerant circuitaccording to the first variation of another embodiment which correspondsto the refrigerant circuit of FIG. 6.

FIG. 13 is a schematic configuration of a main part of an evaporatoraccording to the second variation of another embodiment whichcorresponds to the evaporator of FIG. 2.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will be described in detail belowbased on the drawings.

First Embodiment of Invention

The first embodiment of the present disclosure will be described. Theair conditioner (10) of the present embodiment is provided at a marineair-conditioning system to supply conditioned air to cabins (103), i.e.,rooms.

As shown in FIG. 1, an intake duct (100) and an air supply duct (101)are connected to a casing (11) of the air conditioner (10). The intakeduct (100), the air supply duct (101), and a space which is formed inthe casing (11) and communicates with the intake duct (100) and the airsupply duct (101), form an air passage in which air flows. The indoorair in the cabins (103) and the outdoor air are taken into the intakeduct (100). The indoor air and the outdoor air are mixed, and the mixedair is sent to the air conditioner (10) through the intake duct (100).The air supply duct (101) is connected to a supply opening (102)provided at each of the cabins (103). The air blown out from the airconditioner (10) passes through the air supply duct (101) and isdistributed into the plurality of cabins (103).

As shown in FIG. 2, the air conditioner (10) of the present embodimentincludes a refrigerant circuit (20), a blower (15), and a controller(16). The refrigerant circuit (20), the blower (15), and the controller(16) are housed in the casing (11). In the casing (11), the blower (15)and an evaporator (50), described later, of the refrigerant circuit (20)are located in the space which communicates with the intake duct (100)and the air supply duct (101).

The refrigerant circuit (20) includes a compressor unit (30), acondenser (35), an expansion valve (40), and an evaporator (50). Therefrigerant circuit (20) is filled with a refrigerant. The refrigerantcircuit (20) is a closed circuit formed by sequentially connecting thecompressor unit (30), the condenser (35), the expansion valve (40), andthe evaporator (50) with pipes.

The compressor unit (30) includes three compressors (31, 32, 33). Thenumber of compressors (31, 32, 33) provided in the compressor unit (30)is merely an example. The compressors (31, 32, 33) are hermetic scrollcompressors (31, 32, 33). Each of the compressors (31, 32, 33) has afixed capacity, that is, the rotational speed cannot be changed.

In the compressor unit (30), the three compressors (31, 32, 33) areconnected to each other in parallel. Specifically, suction pipes (31 a,32 a, 33 a) of the compressors (31, 32, 33) are connected to an outletpipe (52) of the evaporator (50), described later. Further, dischargepipes (31 b, 32 b, 33 b) of the compressors (31, 32, 33) are connectedto a refrigerant inlet of the condenser (35). The compressors (31, 32,33) compress the refrigerant suctioned through the suction pipes (31 a,32 a, 33 a) and discharge the compressed refrigerant through thedischarge pipes (31 b, 32 b, 33 b).

The operation capacity of the compressor unit (30) is adjusted bychanging the number of compressors (31, 32, 33) in operation. Ingeneral, the operation capacity of the compressor unit (30) can beadjusted by changing the rotational speed of each compressor (31, 32,33) using an inverter. However, if an inverter is used, electromagneticnoise is generated, and this may adversely affect radio communicationsuch as rescue communication. Further, a negative phase sequence currentgenerated in the inverter may reduce the capability of an electricgenerator. Thus, if an inverter is used to adjust the operation capacityof the compressor unit (30), the marine air conditioner (10) requiresmeasures for preventing the above adverse effects and this may increasethe fabrication costs. For this reason, the compressor unit (30) of thepresent embodiment is configured such that the operation capacity of thecompressor unit (30) is adjusted by changing the number of compressors(31, 32, 33) in operation.

The condenser (35) is a so-called a shell and tube heat exchanger, inwhich a refrigerant is heat exchanged with cooling water (e.g., seawateror water taken from a river etc.). The refrigerant outlet of thecondenser (35) is connected to the evaporator (50) with a pipe (25). Thepipe (25) is provided with the expansion valve (40).

The expansion valve (40) is a so-called thermostatic automatic expansionvalve. A feeler bulb (40 a) of the expansion valve (40) is attached tothe outlet pipe (52) of the evaporator (50), and is in contact with thesurface of the outlet pipe (52).

The pipe (25) is branched into two pipes at a downstream side of theexpansion valve (40). A first branch pipe (26) is connected to one endof a first flow pass (56) of the evaporator (50), and a second branchpipe (27) is connected to one end of a second flow pass (61) of theevaporator (50). The second branch pipe (27) of the pipe (25) isprovided with a solenoid valve (70) which comprises a flow controlmechanism (17).

The evaporator (50) is a so-called cross-fin type fin-and-tube heatexchanger, and includes a heat-transfer tube made of copper and a fin(51) made of aluminum. The evaporator (50) exchanges heat between therefrigerant and air.

The evaporator (50) has a first heat exchanger section (55) and a secondheat exchanger section (60). The heat exchanger section (55, 60) iscomprised of the flow pass (56, 61) made of a heat-transfer tube, andfins (51) attached to the heat-transfer tube comprising the flow pass(56, 61). In the evaporator (50), the fins (51) which comprise the heatexchanger sections (55, 60) are integrally formed.

As described above, in the evaporator (50), one end of the first flowpass (56) is connected to the expansion valve (40) via the first branchpipe (26), and one end of the second flow pass (61) is connected to theexpansion valve (40) via the second branch pipe (27). In the evaporator(50), the other end of each of the flow passes (56, 61) is connected tothe outlet pipe (52).

The air conditioner (10) is provided with a supply air temperaturesensor (81) and an evaporation temperature sensor (82). The supply airtemperature sensor (81) is located at a downstream side of theevaporator (50) along an airflow passage. The supply air temperaturesensor (81) measures a temperature of the air delivered to the airsupply duct (101) through the evaporator (50). The evaporationtemperature sensor (82) is attached to the heat-transfer tube comprisingthe first flow pass (56) of the evaporator (50), and is in contact withthe surface of the heat-transfer tube. The evaporation temperaturesensor (82) measures a. temperature of the surface of the heat-transfertube as a temperature at which the refrigerant evaporates in theevaporator (50).

The controller (16) performs operation of adjusting the operationcapacity of the compressor unit (30), and operation of controlling thesolenoid valve (70). Specifically, a value measured by the supply airtemperature sensor (81), and a value measured by the evaporationtemperature sensor (82) are input to the controller (16). The controller(16) adjusts the operation capacity of the compressor unit (30) based onthe value measured by the supply air temperature sensor (81), andopens/closes the solenoid valve (70) based on the value measured by theevaporation temperature sensor (82).

—Operation Mechanism—

An operation mechanism of the air conditioner (10) will be described.

First, an operation of the refrigerant circuit (20) will be describedwith reference to FIG. 2. In this example, a state in which theoperation capacity of the compressor unit (30) is largest and thesolenoid valve (70) is open will be described.

When the operation capacity of the compressor unit (30) is largest, allthe compressors (31, 32, 33) are operated. The refrigerant dischargedfrom each of the compressors (31, 32, 33) is merged together, flows intothe condenser (35), dissipates heat into cooling water, and iscondensed. The refrigerant condensed in the condenser (35) isdepressurized when passing through the expansion valve (40), and changedto a gas-liquid two-phase state.

The refrigerant having passed through the expansion valve (40) flowsinto the evaporator (50). Specifically, part of the refrigerant havingpassed through the expansion valve (40) goes through the first branchpipe (26) to flow into the first flow pass (56) of the first heatexchanger section (55), and the other part of the refrigerant goesthrough the second branch pipe (27) to flow into the second flow pass(61) of the second heat exchanger section (60). The refrigerant flowingin the flow pass (56, 61) absorbs heat from the air passing between thefins (51) and evaporates, and usually becomes superheated vapors andflows into the outlet pipe (52).

The refrigerant having flowed into the outlet pipe (52) from the flowpasses (56, 61) flows out from the evaporator (50), and is separatelysucked into the three compressors (31, 32, 33) thereafter. Therefrigerant sucked into the compressors (31, 32, 33) is compressed andthereafter discharged from the compressors (31, 32, 33).

As described above, the feeler bulb (40 a) of the expansion valve (40)is attached to the outlet pipe (52) of the evaporator (50). Thus, theopening of the expansion valve (40) is adjusted such that a degree ofsuperheat of the refrigerant flowing in the outlet pipe (52) will be atarget degree of superheat. That is, when the degree of superheat of therefrigerant flowing in the outlet pipe (52) is too high, the opening ofthe expansion valve (40) is increased to lower the degree of superheat.On the other hand, when the degree of superheat of the refrigerantflowing in the outlet pipe (52) is too low, the opening of the expansionvalve (40) is reduced to increase the degree of superheat.

Now, flow of the air will be described with reference to FIG. 1. Theblower (15) is driven during operation of the air conditioner (10). Theblower (15) takes air through the air supply duct (101). Thus, the airin the cabins (103) and the air outside the boat are taken in the airconditioner (10) through the air supply duct (101).

The air taken in the air conditioner (10) is cooled by the refrigerantwhen passing through the evaporator (50). In general, the temperature ofthe air having passed through the evaporator (50) is lower than thedew-point temperature of the air to be delivered to the evaporator (50).Thus, in the evaporator (50), water vapors contained in the air arecondensed into drain water. In other words, the air is cooled anddehumidified in the evaporator (50). The cooled and dehumidified air isdelivered into the air supply duct (101) from the air conditioner (10).The air flowing in the air supply duct (101) is distributed into thesupply opening (102) provided at each cabin (103), and blown into thecabin (103) from the supply opening (102).

—Operation of Controller—

Now, an operation of the controller (16) will be described.

First, an operation for adjusting the operation capacity of thecompressor unit (30) will be described. The controller (16) adjusts theoperation capacity of the compressor unit (30) such that a temperaturemeasured by the supply air temperature sensor (81) will be apredetermined temperature.

Specifically, if the temperature measured by the supply air temperaturesensor (81) is lower than the predetermined temperature, the controller(16) reduces, one by one, the number of compressors (31, 32, 33) inoperation in the compressor unit (30) to increase the value measured bythe supply air temperature sensor (81). That is, in this case, thecontroller (16) reduces the operation capacity of the compressor unit(30) in stages. Further, if the temperature measured by the supply airtemperature sensor (81) is lower than the predetermined temperature evenin a situation where only one of the compressors (31, 32, 33) isoperated, the controller (16) stops all of the compressors (31, 32, 33).

On the other hand, if the temperature measured by the supply airtemperature sensor (81) is higher than the predetermined temperature,the controller (16) increases, one by one, the number of compressors(31, 32, 33) in operation in the compressor unit (30) to reduce thevalue measured by the supply air temperature sensor (81). That is, inthis case, the controller (16) increases the operation capacity of thecompressor unit (30) in stages.

Next, an operation for controlling the solenoid valve (70) will bedescribed. The controller (16) opens/closes the solenoid valve (70) sothat the value measured by the evaporation temperature sensor (82) ismaintained in a predetermined reference range.

Specifically, when the value measured by the evaporation temperaturesensor (82) exceeds an upper limit of the reference range in a statewhere the solenoid valve (70) is open, the controller (16) closes thesolenoid valve (70). In the evaporator (50), if the solenoid valve (70)is closed, the refrigerant does not flow in the second flow pass (61) ofthe second heat exchanger section (60), but flows only in the first flowpass (56) of the first heat exchanger section (55).

If the solenoid valve (70) is open in a state where the operationcapacity of the compressor unit (30) is small, the capacity of theevaporator (50) is too much with respect to the flow rate of therefrigerant which circulates in the refrigerant circuit (20), and it ishighly likely that the temperature at which the refrigerant evaporatesat the evaporator (50) will increase. In such a case, the controller(16) closes the solenoid valve (70) to reduce the capacity of theevaporator (50). If the solenoid valve (70) is closed, the refrigerantflows only to the first flow pass (56), and the capacity of theevaporator (50) is accordingly reduced. Consequently, the evaporationtemperature of the refrigerant at the evaporator (50) is reduced.

On the other hand, if the value measured by the evaporation temperaturesensor (82) is smaller than a lower limit of the reference range in astate where the solenoid valve (70) is closed, the controller (16) opensthe solenoid valve (70). In the evaporator (50), if the solenoid valve(70) is open, the refrigerant flows into both of the first flow pass(56) of the first heat exchanger section (55) and the second heatexchanger section (60) of the first flow pass (56).

If the solenoid valve (70) is closed in a state where the operationcapacity of the compressor unit (30) is large, the capacity of theevaporator (50) is too small with respect to the flow rate of therefrigerant which circulates in the refrigerant circuit (20), and it ishighly likely that the temperature at which the refrigerant evaporatesat the evaporator (50) will decrease. In such a case, the controller(16) opens the solenoid valve (70) to increase the capacity of theevaporator (50). If the solenoid valve (70) is opened, the refrigerantflows to both of the first flow pass (56) and the second flow pass (61),and the capacity of the evaporator (50) is accordingly increased.Consequently, the evaporation temperature of the refrigerant in theevaporator (50) is increased.

Advantages of First Embodiment

As described above, the controller (16) adjusts the operation capacityof the compressor unit (30) during the operation of the air conditioner(10). If the cooling load of the cabins (103) is very small, all thecompressors (31, 32, 33) of the compressor unit (30) may be stopped evenduring the operation of the air conditioner (10). The air conditioner(10) takes air in which indoor air and outdoor air are mixed, andsupplies the mixed air to the cabins (103). In other words, the airconditioner (10) performs not only cooling, but also ventilation of thecabins (103). The cabins (103) need to be ventilated all the time,irrespective of the cooling load of the cabins (103). Therefore, duringthe operation of the air conditioner (10), the blower (15) is keptdriven even in the state where all the compressors (31, 32, 33) of thecompressor unit (30) are stopped.

In the state where all the compressors (31, 32, 33) are stopped, therefrigerant is not supplied to the evaporator (50), and cooling of theair does not occur in the evaporator (50). On the surface of theevaporator (50) or around the evaporator (50), there remains drain watergenerated during the operation of the compressors (31, 32, 33). If airpasses through the evaporator (50) in the state where all thecompressors (31, 32, 33) are stopped, the drain water on the surface ofthe evaporator (50) and around the evaporator (50) is heated by the air,evaporates again, and is delivered to the cabins (103) together with theair. Therefore, if all the compressors (31, 32, 33) of the compressorunit (30) are stopped during the operation of the air conditioner (10),the humidity of the air to be supplied to the cabins (103) increases,which may reduce comfort of the interior of the cabins (103).

In the marine air conditioner (10), in particular, it is difficult touse an inverter in order to adjust the operation capacity of thecompressor unit (30) in terms of cost. Therefore, in general, theoperation capacity of the compressor unit (30) is adjusted by changingthe number of compressors (31, 32, 33) in operation. It is thusdifficult to adjust the operation capacity of the compressor unit (30)in detail, and it frequently happens that all the compressors (31, 32,33) of the compressor unit (30) are stopped.

Further, in the air conditioner (10) of the present embodiment, athermostatic automatic expansion valve is used as the expansion valve(40), and the feeler bulb (40 a) of the expansion valve (40) is attachedto the outlet pipe (52) of the evaporator (50). A degree of superheat ofthe refrigerant flowing in the outlet pipe (52) is increased when thecapacity of the evaporator (50) is too much with respect to the flowrate of the refrigerant which circulates in the refrigerant circuit(20), and therefore, the opening of the expansion valve (40) isincreased to reduce the degree of superheat of the refrigerant. However,in the state where the opening of the expansion valve (40) is large, itis difficult to sufficiently reduce the flow rate of the refrigerantpassing through the evaporator (50) by reducing the number ofcompressors (31, 32, 33) in operation. It is thus difficult tosufficiently reduce the lower limit of a range of adjustment of thecooling capability of the air conditioner (10), and this is also a causeof frequent occurrence of the situation in which all the compressors(31, 32, 33) of the compressor unit (30) are stopped.

In the air conditioner (10) of the present embodiment, the controller(16) controls the solenoid valve (70) based on a value measured by theevaporation temperature sensor (82), thereby changing the number of heatexchanger sections (55, 60) in the evaporator (50) through which therefrigerant flows, such that the value measured by the evaporationtemperature sensor (82) is maintained in a reference range. Thus, forexample, if only one compressor (31, 32, 33) of the compressor unit (30)is in operation and the evaporation temperature of the refrigerant atthe evaporator (50) increases and exceeds the upper limit of thereference range, the controller (16) closes the solenoid valve (70), andthe refrigerant flows only to the first flow pass (56) of the first heatexchanger section (55).

In the air conditioner (10) of the present embodiment, as describedabove, if the flow rate of the refrigerant passing through theevaporator (50) is reduced due to a reduction in the operation capacityof the compressor unit (30), the number of heat exchanger sections (55,60) in the evaporator (50) through which the refrigerant flows isreduced, thereby reducing the capacity of the evaporator (50). Thus, inthe present embodiment, the capacity of the evaporator (50) can bereduced according to the operation capacity of the compressor unit (30),and it is possible to reduce the lower limit of a range of adjustment ofthe cooling capability. As a result, it is possible to reduce thefrequency of the occurrence of the situation where all the compressors(31, 32, 33) of the compressor unit (30) are stopped, and possibilitythat comfort of the indoor space is reduced due to the reevaporation ofdrain water.

Further, in the case where the flow rate of the refrigerant passingthrough the evaporator (50), an excessive increase in the degree ofsuperheat of the refrigerant flowing in the outlet pipe (52) of theevaporator (50) is prevented by reducing the number of heat exchangersections (55, 60) in the evaporator (50) through which the refrigerantflows. Thus, the opening of the expansion valve (40) can be smaller thana certain degree, and it is possible to reliably reduce the flow rate ofthe refrigerant passing through the evaporator (50).

First Variation of First Embodiment

In the evaporator (50) of the first embodiment, one or both of the firstflow pass (56) of the first heat exchanger section (55) and the secondflow pass (61) of the second heat exchanger section (60) may have aplurality of paths (56 a, 56 b, 61 a, 61 b).

In an example shown in FIG. 3, each of the first flow pass (56) and thesecond flow pass (61) includes a first path (56 a, 61 a), a second path(56 b, 61 b), a distributer (57, 62), and a junction pipe (58, 63). Inthe first flow pass (56) shown in FIG. 3, one end of each of the firstpath (56 a) and the second path (56 b) is connected to an outlet side ofthe distributer (57), and the other end of each of the first path (56 a)and the second path (56 b) is connected to the outlet pipe (52) via thejunction pipe (58). The first branch pipe (26) of the pipe (25) isconnected to an intake side of the distributer (57). In the second flowpass (61) shown in FIG. 3, one end of each of the first path (61 a) andthe second path (61 b) is connected to an outlet side of the distributer(62), and the other end of each of the first path (61 a) and the secondpath (61 b) is connected to the outlet pipe (52) via the junction pipe(63). The second branch pipe (27) of the pipe (25) is connected to anintake side of the distributer (62).

In an example shown in FIG. 4, only the second flow pass (61) includesthe first path (61 a), the second path (61 b), the distributer (62), andthe junction pipe (63). In the second flow pass (61) shown in FIG. 4,one end of each of the first path (61 a) and the second path (61 b) isconnected to the outlet side of the distributer (62), and the other endof each of the first path (61 a) and the second path (61 b) is connectedto the outlet pipe (52) via the junction pipe (63). The second branchpipe (27) of the pipe (25) is connected to the intake side of thedistributer (62).

Second Variation of First Embodiment

The evaporator (50) of the first embodiment may include three or moreheat exchanger sections (55, 60, 65). In this example, a refrigerantcircuit (20) provided with an evaporator (50) which includes three heatexchanger sections (55, 60, 65) will be described with reference to FIG.5.

In the refrigerant circuit (20) of the present variation, the pipe (25)connecting the condenser (35) and the evaporator (50) is divided intothree branch pipes (26, 27, 28) at a portion on the downstream side ofthe expansion valve (40). The first branch pipe (26) is connected to oneend of the first flow pass (56) of the first heat exchanger section(55). The second branch pipe (27) is connected to one end of the secondflow pass (61) of the second heat exchanger section (60). The thirdbranch pipe (28) is connected to one end of the third flow pass (66) ofthe third heat exchanger section (65). The other end of each of the flowpasses (56, 61, 66) is connected to the outlet pipe (52). In therefrigerant circuit (20) of the present variation, the second branchpipe (27) of the pipe (25) is provided with a first solenoid valve (71),and the third branch pipe (28) is provided with a second solenoid valve(72). In the evaporator (50) of the present variation, the number ofheat exchanger sections (55, 60, 65) through which the refrigerant flowsis any number from one to three.

Second Embodiment of Invention

The second embodiment of the present disclosure will be described. Arefrigerant circuit (20) of the present embodiment includes the samenumber of expansion valves (41, 42) as the number of heat exchangersections (55, 60) of the evaporator (50).

The refrigerant circuit (20) shown in FIG. 6 is obtained by applying thepresent embodiment to the refrigerant circuit (20) shown in FIG. 2. Inthe refrigerant circuit (20) shown in FIG. 6, branch pipes (26, 27) ofthe pipe (25) are provided with expansion valves (41, 42), respectively.The second expansion valve (42) is provided on the second branch pipe(27) of the pipe (25) at a location on the upstream side of the solenoidvalve (70).

Each of the expansion valves (41, 42) of the refrigerant circuit (20)shown in FIG. 6 is a so-called thermostatic automatic expansion valve. Afeeler bulb (41 a) of the first expansion valve (41) provided at thefirst branch pipe (26) is attached to a pipe which comprises an outletside end of the first flow pass (56), and is in contact with a surfaceof this pipe. The opening of the first expansion valve (41) is adjustedsuch that a degree of superheat of the refrigerant flowing out of thefirst heat exchanger section (55) will be a target degree of superheat.A feeler bulb (42 a) of the second expansion valve (42) provided at thesecond branch pipe (27) is attached to a pipe which comprises an outletside end of the second flow pass (61), and is in contact with a surfaceof this pipe. The opening of the second expansion valve (42) is adjustedsuch that a degree of superheat of the refrigerant flowing out of thesecond heat exchanger section (60) will be a target degree of superheat.

The refrigerant circuit (20) shown in FIG. 7 is obtained by applying thepresent embodiment to the refrigerant circuit (20) shown in FIG. 3. Inthe refrigerant circuit (20) shown in FIG. 7, branch pipes (26, 27) ofthe pipe (25) are provided with expansion valves (41, 42), respectively.The second expansion valve (42) is provided on the second branch pipe(27) of the pipe (25) at a location on the upstream side of the solenoidvalve (70).

Each of the expansion valves (41, 42) of the refrigerant circuit (20)shown in FIG. 7 is a so-called thermostatic automatic expansion valve. Afeeler bulb (41 a) of the first expansion valve (41) provided at thefirst branch pipe (26) is attached to a junction pipe (58) of the firstflow pass (56), and is in contact with a surface of the junction pipe(58). The opening of the first expansion valve (41) is adjusted suchthat a degree of superheat of the refrigerant flowing out of the paths(56 a, 56 b) of the first heat exchanger section (55) will be a targetdegree of superheat. A feeler bulb (42 a) of the second expansion valve(42) provided at the second branch pipe (27) is attached to a junctionpipe (63) of the second flow pass (61), and is in contact with a surfaceof the junction pipe (63). The opening of the second expansion valve(42) is adjusted such that a degree of superheat of the refrigerantflowing out of the paths (61 a, 61 b) of the second heat exchangersection (60) will be a target degree of superheat.

The refrigerant circuit (20) shown in FIG. 8 is obtained by applying thepresent embodiment to the refrigerant circuit (20) shown in FIG. 4. Inthe refrigerant circuit (20) shown in FIG. 8, branch pipes (26, 27) ofthe pipe (25) are provided with expansion valves (41, 42), respectively.The second expansion valve (42) is provided on the second branch pipe(27) of the pipe (25) at a location on the upstream side of the solenoidvalve (70).

Each of the expansion valves (41, 42) of the refrigerant circuit (20)shown in FIG. 8 is a so-called thermostatic automatic expansion valve. Afeeler bulb (41 a) of the first expansion valve (41) provided at thefirst branch pipe (26) is attached to a pipe which comprises an outletside end of the first flow pass (56), and is in contact with a surfaceof this pipe. The opening of the first expansion valve (41) is adjustedsuch that a degree of superheat of the refrigerant flowing out of thefirst heat exchanger section (55) will be a target degree of superheat.A feeler bulb (42 a) of the second expansion valve (42) provided at thesecond branch pipe (27) is attached to a junction pipe (63) of thesecond flow pass (61), and is in contact with a surface of the junctionpipe (63). The opening of the second expansion valve (42) is adjustedsuch that a degree of superheat of the refrigerant flowing out of thepaths (61 a, 61 b) of the second heat exchanger section (60) will be atarget degree of superheat.

The refrigerant circuit (20) shown in FIG. 9 is obtained by applying thepresent embodiment to the refrigerant circuit (20) shown in FIG. 5. Inthe refrigerant circuit (20) shown in FIG. 9, branch pipes (26, 27, 28)of the pipe (25) are provided with expansion valves (41, 42, 43),respectively. The second expansion valve (42) is provided on the secondbranch pipe (27) of the pipe (25) at a location on the upstream side ofthe first solenoid valve (71). The third expansion valve (43) isprovided on the third branch pipe (28) of the pipe (25) at a location onthe upstream side of the second solenoid valve (72).

Each of the expansion valves (41, 42, 43) of the refrigerant circuit(20) shown in FIG. 9 is a so-called thermostatic automatic expansionvalve. A feeler bulb (41 a) of the first expansion valve (41) providedat the first branch pipe (26) is attached to a pipe which comprises anoutlet side end of the first flow pass (56), and is in contact with asurface of this pipe. The opening of the first expansion valve (41) isadjusted such that a degree of superheat of the refrigerant flowing outof the first heat exchanger section (55) will be a target degree ofsuperheat. A feeler bulb (42 a) of the second expansion valve (42)provided at the second branch pipe (27) is attached to a pipe whichcomprises an outlet side end of the second flow pass (61), and is incontact with a surface of this pipe. The opening of the second expansionvalve (42) is adjusted such that a degree of superheat of therefrigerant flowing out of the second heat exchanger section (60) willbe a target degree of superheat. A feeler bulb (43 a) of the thirdexpansion valve (43) provided at the third branch pipe (28) is attachedto a pipe which comprises an outlet side end of the third flow pass(66), and is in contact with a surface of this pipe. The opening of thethird expansion valve (43) is adjusted such that a degree of superheatof the refrigerant flowing out of the third heat exchanger section (65)will be a target degree of superheat.

Variation of Second Embodiment

In the refrigerant circuit (20) of the present embodiment, the expansionvalve (42, 43) and the solenoid valve (71, 72) may change places witheach other at the branch pipe (27, 28) of the pipe (25).

The refrigerant circuit (20) shown in FIG. 10 is obtained by applyingthe present variation to the refrigerant circuit (20) shown in FIG. 6. Asecond expansion valve (42) is provided on the second branch pipe (27)of the refrigerant circuit (20) shown in FIG. 10 at a location on thedownstream side of the solenoid valve (70).

Other Embodiments

—First Variation—

The refrigerant circuits (20) shown in FIG. 2 to FIG. 10 may include aso-called electronic expansion valve as the expansion valve (40, 41,42).

The refrigerant circuit (20) shown in FIG. 11 is obtained by applyingthe present variation to the refrigerant circuit (20) shown in FIG. 2.

In the refrigerant circuit (20) shown in FIG. 11, a refrigeranttemperature sensor (85) is attached to the outlet pipe (52) of theevaporator (50). The refrigerant temperature sensor (85) is in contactwith the outlet pipe (52) and measures a temperature of a surface of theoutlet pipe (52) as a temperature of the refrigerant flowing in theoutlet pipe (52). A degree of superheat of the refrigerant flowing inthe outlet pipe (52) can be calculated by subtracting a value measuredby the evaporation temperature sensor (82) from a value measured by therefrigerant temperature sensor (85). The controller (16) of the presentvariation controls the opening of the expansion valve (40) in therefrigerant circuit (20) shown in FIG. 11 such that the value obtainedby subtracting the value measured by the evaporation temperature sensor(82) from the value measured by the refrigerant temperature sensor (85)will be a target degree of superheat.

The refrigerant circuit (20) shown in FIG. 12 is obtained by applyingthe present variation to the refrigerant circuit (20) shown in FIG. 6.

In the refrigerant circuit (20) shown in FIG. 12, a first refrigeranttemperature sensor (86) is attached to a pipe which comprises an outletside end of the first flow pass (56). The first refrigerant temperaturesensor (86) is in contact with the pipe and measures a temperature of asurface of the pipe as a temperature of the refrigerant flowing out fromthe first flow pass (56). A degree of superheat of the refrigerantflowing out of the first flow pass (56) can be calculated by subtractinga value measured by the evaporation temperature sensor (82) from a valuemeasured by the first refrigerant temperature sensor (86). Thecontroller (16) of the present variation adjusts the opening of thefirst expansion valve (41) in the refrigerant circuit (20) shown in FIG.12 such that the value obtained by subtracting the value measured by theevaporation temperature sensor (82) from the value measured by the firstrefrigerant temperature sensor (86) will be a target degree ofsuperheat.

Further, in the refrigerant circuit (20) shown in FIG. 12, a secondrefrigerant temperature sensor (87) is attached to a pipe whichcomprises an outlet side end of the second flow pass (61). The secondrefrigerant temperature sensor (87) is in contact with the pipe andmeasures a temperature of a surface of the pipe as a temperature of therefrigerant flowing out of the second flow pass (61). A degree ofsuperheat of the refrigerant flowing out of the second flow pass (61)can be calculated by subtracting a value measured by the evaporationtemperature sensor (82) from a value measured by the second refrigeranttemperature sensor (87). The controller (16) of the present variationadjusts the opening of the second expansion valve (42) in therefrigerant circuit (20) shown in FIG. 12 such that the value obtainedby subtracting the value measured by the evaporation temperature sensor(82) from the value measured by the second refrigerant temperaturesensor (87) will be a target degree of superheat.

A solenoid valve (70) is omitted in the refrigerant circuit (20) shownin FIG. 12. That is, only the second expansion valve (42) is provided onthe second branch pipe (27) of the pipe (25). In this refrigerantcircuit (20), the second expansion valve (42) also serves as a flowcontrol mechanism (17). That is, the opening of the second expansionvalve (42), which is an electronic expansion valve, can be freelydetermined by a control signal from the controller (16). Thus, in thecase where the refrigerant is intended to flow only in the first flowpass (56), the controller (16) closes the second expansion valve (42)completely.

—Second Variation—

In the evaporator (50) shown in FIG. 2 to FIG. 10, heat-transfer tubescomprising the flow passes (56, 61, 66) may be alternately arranged.

The evaporator (50) shown in FIG. 13 is obtained by applying the presentvariation to the evaporator (50) shown in FIG. 2. In the evaporator (50)shown in FIG. 13, a heat-transfer tube comprising the first flow pass(56) and a heat-transfer tube comprising the second flow pass (61) arealternately arranged in a longitudinal direction of the fin (51). Theevaporator (50) of the present variation allows the air passing throughthe evaporator (50) to have a uniform temperature even in the statewhere the refrigerant flows only in the first flow pass (56).

—Third Variation—

The controller (16) of the above embodiments may be configured to changethe number of heat exchanger sections (55, 60, 65) through which therefrigerant flows in the evaporator (50), based on an evaporationpressure of the refrigerant in the evaporator (50). In this example, thepresent variation is applied to the air conditioner (10) of the firstembodiment shown in FIG. 2.

The controller (16) of the present variation opens/closes the solenoidvalve (70) such that an evaporation pressure of the refrigerant in theevaporator (50) (i.e., a low pressure of refrigeration cycle) ismaintained in a reference range.

Specifically, when the evaporation pressure of the refrigerant exceedsan upper limit of the reference range in the state where the solenoidvalve (70) is open, the controller (16) closes the solenoid valve (70).In the state where the solenoid valve (70) is closed, the refrigerantdoes not flow into the second flow pass (61) of the second heatexchanger section (60) in the evaporator (50), but flows only into thefirst flow pass (56) of the first heat exchanger section (55).

If the solenoid valve (70) is open in the state where the operationcapacity of the compressor unit (30) is small, the capacity of theevaporator (50) is too much with respect to the flow rate of therefrigerant which circulates in the refrigerant circuit (20), and it ishighly likely that the temperature at which the refrigerant evaporatesat the evaporator (50) will increase. In such a case, the controller(16) closes the solenoid valve (70) to reduce the capacity of theevaporator (50). When the solenoid valve (70) is closed, the refrigerantflows only to the first flow pass (56), and the capacity of theevaporator (50) is accordingly reduced. Consequently, the evaporationtemperature of the refrigerant at the evaporator (50) is reduced.

On the other hand, if the evaporation pressure of the refrigerant in theevaporator (50) is lower than a lower limit of the reference range inthe state where the solenoid valve (70) is closed, the controller (16)opens the solenoid valve (70). In the state where the solenoid valve(70) is open, the refrigerant flows into both of the first flow pass(56) of the first heat exchanger section (55) and the second flow pass(61) of the second heat exchanger section (60) in the evaporator (50).

If the solenoid valve (70) is closed in the state where the operationcapacity of the compressor unit (30) is large, the capacity of theevaporator (50) is too small with respect to the flow rate of therefrigerant which circulates in the refrigerant circuit (20), and it ishighly likely that the evaporation pressure of the refrigerant in theevaporator (50) decreases. In such a case, the controller (16) opens thesolenoid valve (70) to increase the capacity of the evaporator (50).When the solenoid valve (70) is open, the refrigerant flows into both ofthe first flow pass (56) and the second flow pass (61), and the capacityof the evaporator (50) is accordingly increased. Consequently, theevaporation pressure of the refrigerant in the evaporator (50) isincreased.

—Fourth Variation—

The controller (16) of the above embodiments may be configured to changethe number of heat exchanger sections (55, 60, 65) through which therefrigerant flows in the evaporator (50), based on a value measured bythe supply air temperature sensor (81). In this example, the presentvariation is applied to the air conditioner (10) of the first embodimentshown in FIG. 2.

The controller (16) of the present variation adjusts the operationcapacity of the compressor unit (30) and controls the solenoid valve(70) such that a value measured by the supply air temperature sensor(81) will be a predetermined temperature.

Specifically, if the temperature measured by the supply air temperaturesensor (81) is lower than the predetermined temperature in the statewhere the solenoid valve (70) is open, the controller (16) reduces, oneby one, the number of compressors (31, 32, 33) in operation in thecompressor unit (30) to increase the value measured by the supply airtemperature sensor (81). Further, if the temperature measured by thesupply air temperature sensor (81) is lower than the predeterminedtemperature even in a state where only one of the compressors (31, 32,33) is operated in the compressor unit (30), the controller (16) closesthe solenoid valve (70). In the state where the solenoid valve (70) isclosed, the refrigerant does not flow into the second flow pass (61) ofthe second heat exchanger section (60) in the evaporator (50), but flowsonly to the first flow pass (56) of the first heat exchanger section(55).

If the solenoid valve (70) is open in the state where only one of thecompressors (31, 32, 33) is in operation, the capacity of the evaporator(50) is too much, and therefore it is highly likely that the temperatureof the air having passed through the evaporator (50) still remains lowerthan the predetermined temperature. In such a case, the controller (16)closes the solenoid valve (70) to reduce the capacity of the evaporator(50). If the solenoid valve (70) is closed, the refrigerant flows onlyto the first flow pass (56), and the capacity of the evaporator (50) isaccordingly reduced. Consequently, the temperature of the air havingpassed through the evaporator (50) is increased.

On the other hand, if the temperature measured by the supply airtemperature sensor (81) is higher than the predetermined temperature inthe state where the solenoid valve (70) is closed, the controller (16)increases, one by one, the number of compressors (31, 32, 33) inoperation in the compressor unit (30) to reduce the value measured bythe supply air temperature sensor (81). Further, if the temperaturemeasured by the supply air temperature sensor (81) is still higher thanthe predetermined temperature even in a situation where only two of thecompressors (31, 32, 33) are operated in the compressor unit (30), thecontroller (16) opens the solenoid valve (70). In the state where thesolenoid valve (70) is open, the refrigerant flows into both of thefirst flow pass (56) of the first heat exchanger section (55) and thesecond flow pass (61) of the second heat exchanger section (60) in theevaporator (50).

If the solenoid valve (70) is closed in the state where two of thecompressors (31, 32, 33) are operated, the capacity of the evaporator(50) is too small with respect to the flow rate of the refrigerant whichcirculates in the refrigerant circuit (20), and it is highly likely thatthe temperature of the air having passed through the evaporator (50)still remains higher than the predetermined temperature. In such a case,the controller (16) opens the solenoid valve (70) to increase thecapacity of the evaporator (50). If the solenoid valve (70) is open, therefrigerant flows into both of the first flow pass (56) and the secondflow pass (61), and the capacity of the evaporator (50) is accordinglyincreased. Consequently, the temperature of the air having passedthrough the evaporator (50) is reduced.

—Fifth Variation—

The controller (16) of the above embodiments may be configured to changethe number of compressors (31, 32, 33) in operation in the compressorunit (30), and also change the number of heat exchanger sections (55,60, 65) through which the refrigerant flows in the evaporator (50). Inthis example, the present variation is applied to the air conditioner(10) of the first embodiment shown in FIG. 2.

As described above, the controller (16) of the first embodiment adjuststhe operation capacity of the compressor unit (30) such that the valuemeasured by the supply air temperature sensor (81) will be apredetermined temperature. When the number of compressors (31, 32, 33)operating in the compressor unit (30) is reduced to two to one, thecontroller (16) closes the solenoid valve (70) simultaneously. When thenumber of compressors (31, 32, 33) operating in the compressor unit (30)is increased from one to two, the controller (16) opens the solenoidvalve (70) simultaneously.

The foregoing embodiments are merely preferred examples in nature, andare not intended to limit the scope, applications, and use of thepresent disclosure.

INDUSTRIAL APPLICABILITY

As described above, the present disclosure is useful as an airconditioner which cools air to be supplied to an indoor space through aduct.

Description of Reference Characters

10 air conditioner

17 flow control mechanism

20 refrigerant circuit

26 first branch pipe

27 second branch pipe

28 third branch pipe

30 compressor unit

31 first compressor

32 second compressor

33 third compressor

35 condenser

40 expansion valve

41 first expansion valve

42 second expansion valve

43 third expansion valve

50 evaporator

55 first heat exchanger section

56 first flow pass

60 second heat exchanger section

61 second flow pass

65 third heat exchanger section

66 third flow pass

1. An air conditioner, comprising: a refrigerant circuit which performsa refrigeration cycle by circulating a refrigerant, for cooling airflowing in an air passage connected to a supply opening of each of aplurality of rooms by the refrigerant, wherein the refrigerant circuitincludes a compressor unit having a plurality of compressors connectedto each other in parallel, an evaporator provided at the air passage andhaving a plurality of heat exchanger sections connected to each other inparallel to heat exchange the refrigerant with the air, and a flowcontrol mechanism configured to change the number of the heat exchangersections through which the refrigerant passes.
 2. The air conditioner ofclaim 1, wherein the flow control mechanism changes the number of theheat exchanger sections through which the refrigerant passes, accordingto an operation capacity of the compressor unit.
 3. The air conditionerof claim 2, wherein each of the compressors in the compressor unit has afixed capacity, the compressor unit is configured such that theoperation capacity of the compressor unit is adjusted by changing thenumber of the compressors in operation, and the flow control mechanismreduces the number of the heat exchanger sections through which therefrigerant passes, when the number of the compressors in operation isreduced.
 4. The air conditioner of claim 1, wherein the refrigerantcircuit is provided with one expansion valve which expands therefrigerant that is not yet branched for flowing into the heat exchangersections of the evaporator.
 5. The air conditioner of claim 1, whereinthe refrigerant circuit is provided with a plurality of branch pipeseach of which is connected to a corresponding one of the heat exchangersections of the evaporator, and through which the refrigerant that isbranched for flowing into the heat exchanger sections flows, and each ofthe branch pipes is provided with a corresponding one of expansionvalves which expand the refrigerant.
 6. The air conditioner of claim 2,wherein the refrigerant circuit is provided with one expansion valvewhich expands the refrigerant that is not yet branched for flowing intothe heat exchanger sections of the evaporator.
 7. The air conditioner ofclaim 3, wherein the refrigerant circuit is provided with one expansionvalve which expands the refrigerant that is not yet branched for flowinginto the heat exchanger sections of the evaporator.
 8. The airconditioner of claim 2, wherein the refrigerant circuit is provided witha plurality of branch pipes each of which is connected to acorresponding one of the heat exchanger sections of the evaporator, andthrough which the refrigerant that is branched for flowing into the heatexchanger sections flows, and each of the branch pipes is provided witha corresponding one of expansion valves which expand the refrigerant. 9.The air conditioner of claim 3, wherein the refrigerant circuit isprovided with a plurality of branch pipes each of which is connected toa corresponding one of the heat exchanger sections of the evaporator,and through which the refrigerant that is branched for flowing into theheat exchanger sections flows, and each of the branch pipes is providedwith a corresponding one of expansion valves which expand therefrigerant.